Surface Abundances of Light Elements as Diagnostics of Transport Processes in the Sun and Solar-Type Stars
Observations of the surface abundances of lithium, beryllium and helium-3 in the Sun and in solar-type stars of different ages should be interpreted in a coherent way. The abundance of lithium at the surface of a star decreases slowly with age; for stars of the same age it decreases with mass and a dependence on the rotation velocity is suggested. The solar surface lithium is depleted by a factor of 100 relative to the cosmic abundance while an He-3 enrichment of 15% at the solar surface during evolution is suggested.
Observations favour the hypothesis of a slow transport process at work between the outer convective zone and the radiative interior of these stars. Orders of magnitude of the transport coefficient as well as its dependence upon the physical parameters can be inferred from surface abundances of light elements, but at the moment we are far from producing a completely consistent modelization.
KeywordsSpectral Type Convective Zone Surface Abundance Lithium Abundance Standard Solar Model
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